That is a verty significant increase in mud gas. The fact that they had to increase mud density suggests the gas zone also has good pressure. The drill pipe becoming stuck is almost certainly related to the increase in mud density. You can get differential sticking within in a porous zone when mud density is elevated.
These are all difficult operational issues especially when encountered in newer/poorly drilled areas. However, all of these issues point to a positive flow test, should they be able to get to that point.
There is also a disticnt possibilty that the zone penetrated was their primary target ... encountered significantly up-structure from pre-drill estimates. Possible ... but not certain.